With advancement in technology, digital still cameras (also called digital cameras) have rapidly become prevalent, and mobile phones having integrated cameras are now commodity. This has led to the increasing needs for techniques to realize downsized camera devices. Another requirement for camera devices is that images taken with them must have a high image quality.
Generally speaking, a camera device includes a lens unit composed of a plurality of lenses for forming an image on the imaging surface of an imaging device. The performance of a camera device, such as resolution, is considerably influenced by the design of a barrel of the lens unit, precision of the parts, precision of assembly when installing the lenses, and so on. Therefore, when assembling a lens unit, attention must be paid to the method of adjustment when installing the lenses.
Patent Document 1 discloses a method of interconnecting a plurality of lenses, with their optical axes being adjusted, to produce a lens block of an integral structure. With reference to FIG. 20 and FIG. 21, the conventional lens block assembly method disclosed in Patent Document 1 will be described.
FIG. 20 is a perspective view showing a procedure of inserting lenses into a fixing jig, and FIG. 21 is a view of a cross section containing the optical axis of the lenses having been inserted into the fixing jig. As shown in FIG. 20, a first lens 810, a second lens 820, a third lens 830, and a fourth lens 840 are sequentially installed into a fixing jig 710, such that, as shown in FIG. 21, the lenses, one being stacked upon another, are supported by the fixing jig 710.
In this state, an adhesive is injected through first throughholes 711A, 711B, and 711C, second throughholes 712A, 712B, and 712C, third throughholes 713A, 713B, and 713C, and fourth throughholes 714A, 714B, and 714C penetrating through the fixing jig 710 from its outer surface to its inner surface, whereby the first lens 810, the second lens 820, the third lens 830, and the fourth lens 840 are adhesively bonded to one another. As a result, a lens block with the four integral lenses is completed. According to Patent Document 1, radial deviation of the lenses can be adjusted by inserting a jig rod into each throughhole and moving the lenses before the adhesive bonding. The assembled lens block is fixed to a barrel of the camera device.
On the other hand, Patent Document 2 and Patent Document 3 disclose methods where radial deviation of lenses with respect to a lens barrel 710 is adjusted by inserting a jig via throughholes like the first throughholes 711A, 711B, and 711C, second throughholes 712A, 712B, and 712C, third throughholes 713A, 713B, and 713C, and fourth throughholes 714A, 714B, and 714C shown in FIG. 20 and FIG. 21.